1. Field of the Invention
The present invention relates to disk drives for the mass storage of information in computer systems, and more particularly to an actuator latching assembly that releasably secures the actuator in a predetermined position when the disk drive remains inoperative and automatically releases the actuator upon activation of the motor of the drive.
2. Description of the Prior Art
A disk drive that provides mass storage of information in computer systems typically includes a disk or a stack of disks and a hub mounted on a rotatable spindle. An actuator controls an array of transducers that write and read binary digital information on the disks. During operation of the disk drive, the actuator rotates about a pivot in response to electromagnetic forces generated by a voice coil motor and places the transducers in desired positions. When the drive does not operate, a latching assembly normally secures the actuator in a predetermined position to protect it and the other components of the drive.
Prior disk drives have included various latching assemblies, including conventional magnetic latches, solenoid latches, and inertial latches. These prior latches suffer a number of disadvantages. For example, conventional magnetic latches require biasing forces on the actuator during latching and unlatching procedures. Prior solenoid latches require electrical power; and inertial latches do not operate under all shock conditions.
The latching assembly of the present invention avoids the disadvantages of the prior art. It provides a positive locking action when the disk drive remains inoperative and automatic release of the actuator upon activation of the drive motor. It is a simple construction that minimizes the expense of fabrication and assembly; and it provides consistent and precise locking and unlocking actions.
In accordance with one embodiment of this invention, a disk drive includes a base, an actuator pivotally mounted on the base, a motor and a hub for supporting the disk or disks of the drive. A rotatable member disposed on the base includes a latch that cooperates with a hook on the actuator and a magnet that cooperates with a ferromagnetic segment disposed between the rotatable member and the motor. When the motor stops, this rotatable member moves to a predetermined position in which the latch engages a hook portion on the actuator. It remains in this position while the motor remains inoperative. Upon activation of the motor, an electromotive force develops between the motor and the rotatable member, causing the rotatable member to move out of the locking position. The rotatable member remains in this unlocked position while the motor operates.